I'd been seeing some weird crashes and refusals to boot from ProDOS on my Apple IIe, so I decided to run some tests. The built in diagnostic said everything was fine. Using the Apple IIe Diagnostic Software, it said there was a main memory failure, and running MECC's (the people who made Oregon Trail) Computer Inspector told me there was a problem in the auxiliary memory but main memory was fine. Ugh.
I ended up using RAM Test Utility and it gave much better information. It was able to tell me that the problem was a stuck bit in my auxiliary memory, and even which chip it was. I swapped the chip with another one on the board to test, and the error moved to that socket so I knew I'd found the problem. I really lucked out in that all the DRAM was both socketed and the sockets were numbered.
Problem. This board uses 4264 DRAM, and that's scarce on eBay or otherwise. Google told me that 4264's are backwards compatible with the more common 4164, but not vice-versa. I decided to risk $20 and ordered a big ol' tube of 4164 chips in the hope that they used 4264's because they were cheaper or more available at the time. Swapped the chip out, and success! Fixed all the sporadic problems I'd been having.
Next up: Have a IIe enhancement kit on order, and once it shows up I'll be able to run ProTerm with the WiModem232 that came in last week. I'm already active on a few BBS's, so I look forward to checking into them from the IIe rather than SyncTERM or DOSBox/Telemate. I ordered a 3D printed case for it, but I'd love to get an old 2400 baud modem and replace its guts with the WiModem. But those are actually more expensive than I'm willing to pay, so itty bitty 3-D printed for now it is.